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From "Xavier Hanin" <xavier.ha...@gmail.com>
Subject Re: ivy:retrieve performance
Date Thu, 14 Jun 2007 13:22:07 GMT
On 6/14/07, Gilles Scokart <gscokart@gmail.com> wrote:
>
> > 2. The buffer in FileUtils.java is too small. It's set at 8192. It seems
> > to
> > > be much better for me to set it much larger. This is due to the fact
> > that
> > > it
> > > needs to read and write simultaneously. The bigger the buffer is, the
> > > smaller number of time, HD header has to move. For me, 65536 seems to
> > > perform much better but I haven't tried other numbers.
> >
> >
> > I'd like to get more feedback on this. One use case is not the other.
> This
> > size has been borrowed from Ant copy mechanism. Maybe what we could do
> is
> > make this configurable, so that one could adapt to its needs. Or try to
> > guess a good size depending on the size (when it's possible to get an
> idea
> > of the size before copying).
> >
> > Xavier
> >
>
>
> Couldn't we use the nio for that?  (See
> http://www.javalobby.org/java/forums/t17036.html)


According to comments 10 and 11 NIO have bad performance for large files on
linux, and input stream with byte buffer is pretty close to NIO for small
files (see comment 13 conclusion). So I'm not sure switching to NIO would
indeed help a lot. According to the tests in the thread you pointed using a
64kB buffer seems to be a good choice (which confirms  testn tests), at
least for large files. OTOH the last conclusion (comment 17) is different.
So I don't really know what to think about that. We should make some tests
on several platforms and jvms to draw conclusion ourself, but it takes time.


Xavier

Gilles
>
>
>
>


-- 
Xavier Hanin - Independent Java Consultant
Manage your dependencies with Ivy!
http://incubator.apache.org/ivy/

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